Modern day telephone technology, especially as used in large metropolitan areas, includes large numbers of dispersed, control apparatus. Such remote terminal units, such as SLC 96 Channel Systems used by Southwestern Bell Telephone Company, must periodically be tested for repair or for preventive maintenance purposes. Pin-Plug carrying blocks are removably plugged into apertures contained by the control apparatus, and test equipment establishes electrical communication with the internal circuitry of said apparatus there through. The linkage between the test equipment and the movable blocks has in itself caused harm to the control apparatus. An important source of such harm has been the unstable means of securing test equipment clips to the pin portion of a plug carried by said blocks. This invention attacks the problem by substantially varying the configuration of the block's pins.